Disc drive isolation system

ABSTRACT

A disc drive isolation system including a disc drive isolation module is disclosed. The isolation module is disposed in the enclosure and has an outer body and an inner body supported within the outer body with the disc drive mounted within the inner body. The mounting of the inner body within the outer body sequesters the disc drive against vibration and shock applied to the outer body. This arrangement enables almost any disc drive to be operated in an industrial environment independent of the shock and vibration characteristics of the environment.

This is a division of application Ser. No. 754,618, filed July 15, 1985,now issued as U.S. Pat. No. 4,685,303.

BACKGROUND OF THE INVENTION

This invention relates to mounting enclosures for disc drive computermemory devices.

Disc drive memory devices usually have a storage medium and a read/writehead to read from or write on the storage medium. The storage medium maybe in the form of a disc or drum and may be rotationally driven at highspeeds. The read/write head must write or read data to or from themedium at a particular position on the medium. Also, in some disc drivedevices the read/write head is spaced closely to the medium, which maybe rotating at a high speed. In such devices, contact between the headand the medium can destroy the head and the medium and result in theperpetual loss of the information stored on the medium.

Factory automation requires the presence of disc drive memory devices inindustrial environments. Vibrations and shock abound in industrialenvironments which can result in the destruction of the head, the mediumand the loss of the information on the medium. It can also causeread/write errors which result in the malfunction of machines controlledby the information from the disc drive. Also, the air can be less thanpure and also may be too hot, too cold or too humid for the disc driveto operate. For the reliable and efficient operation of disc drives inindustrial environments, a need exists for an enclosure for a disc driveto shelter the disc drive from the exterior environment.

SUMMARY OF THE INVENTION

The invention provides a disc drive isolation system for protecting adisc drive in an industrial environment. A disc drive isolation systemof the invention includes a disc drive isolation module. The disc driveis mounted within the module and is sequestered therein from vibrationsand shocks applied to the exterior of the module and the module isreceived within the interior of the enclosure.

Highly reliable operation of the disc drive is thus assured as it is notaffected by shocks and vibrations to which the enclosure is subjected.

In another aspect of the invention, the disc drive isolation modulecomprises a structurally rigid outer body defining an inner space. Astructurally rigid inner body of symmetrical shape is smaller than theouter body and fits within the inner space defined by the outer body.The inner body is supported within the outer body by sets of biasingmeans to have three translational degrees of freedom and threerotational degrees of freedom. The disc drive is rigidly mounted withinthe inner body so that it is subjected to the shocks and vibrations thatthe inner body experiences. The translational displacement of the innerbody within the outer body is at least 0.89 mm (0.035 inches) in alldirections to protect the disc drive against high amplitude, lowfrequency vibration and shock which is common in industrialenvironments. The inner body is symmetrical to equalize inertial momentsabout the rotational axes. This arrangement isolates the disc drive fromshock and vibration which could otherwise cause read/write errors ordamage to the disc drive.

In an especially useful embodiment, first biasing means comprising apair of extension springs are connected between the top sides of theinner and outer bodies to suspend the inner body within the outer bodyand second biasing means comprising a pair of compression springs areconnected between the bottom sides of the inner and outer bodies forsupporting the inner body within the outer body. Damping means aredisposed between the inner and outer bodies on the top, bottom, left,right, front and rear sides of the inner and outer bodies, each saiddamping means terminating short of spanning the inner and outer bodiesto permit the required displacement of the inner body. The springs ofthe first biasing means are diagonally opposed from the springs of thesecond biasing means to eliminate bobbing effects of the inner body. Thedamping means absorb higher level shocks that cause the inner module toexceed the permitted displacement.

In another aspect, each of the inner and outer bodies of the disc driveisolation module is made up of six identical plates which are fastenedtogether to form either the inner or the outer body. Each plate has aflat rectangular inner portion, two pairs of first ears and two pairs ofsecond ears. The ears are symmetrically disposed along the edges of therectangular portion with each pair of first ears being opposite from theother pair of first ears and with each pair of second ears opposite fromthe other pair of second ears. Each ear has an outer and an inner holewith the center of each hole lying on a line which extends through thecenters of the holes in the opposite ear. The ears of adjacent platesare fastened together to form either the inner or the outer body,depending upon which holes in the ears are used.

It is therefore a primary object of the invention to provide a discdrive isolation system which enables a disc drive to operate in anindustrial environment.

It is another object of the invention to provide a disc drive isolationsystem to eliminate shock and vibration variables to which a disc driveis subjected in an industrial environment.

It is another object of the invention to provide a disc drive isolationmodule for sequestering almost any disc drive from vibration and shockapplied to the exterior of the module.

It is another object of the invention to provide a disc drive isolationmodule which can be easily and inexpensively provided.

It is another object of the invention to provide a disc drive isolationsystem which results in the highly reliable operation of a disc drive inthe industrial environment.

These and other objects and advantages of the invention will becomeclear from the following detailed description and from the drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a disc drive isolation system ofthe invention;

FIG. 2 is a perspective view of the system of FIG. 1 as viewed from therear;

FIG. 3 is a perspective view similar to FIG. 1 with the door of thesystem removed;

FIG. 4 is a fragmentary front plane view of the system with the doorremoved;

FIG. 5 is a side plan view partially in section of the disc driveisolation system;

FIG. 6 is perspective view of a disc drive isolation module for the discdrive isolation system;

FIG. 7 is a front plan view partially in section of the disc driveisolation module of FIG. 6 illustrating a front pair of pads in phantom;

FIG. 8 is an exploded perspective view of a portion of the disc driveisolation module of FIG. 6;

FIG. 9 is a plan view of a plate used to make the disc drive isolationmodule of FIG. 6;

FIG. 10 is a side plan view of the plate of FIG. 9;

FIG. 11 is a sectional view taken along the plane of the line 11-11 ofFIG. 9;

FIG. 12 is a graph comparing the results of testing a disc drive aloneand testing it within the disc drive isolation module of FIG. 6;

FIG. 13 is a sectional view of a means for mounting a heat pump to anenclosure of the disc drive isolation system;

FIG. 14 is a control circuit for the heating and cooling means for thedisc drive isolation system; and

FIG. 15 is a schematic view of a control circuit for the disc driveisolation system to control the disc drive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 illustrate a disc drive isolation system 8 which includesan enclosure 10. The exterior of the enclosure 10 is formed by a sheetmetal chassis 12 along the top, bottom, sides and rear, a heat pump 14at the upper rear corner, and a rigid sheet metal door 16 which issecured to the front. Data cables 18 and 19 and a power cable 20 enterthe bottom of the enclosure. The chassis 12 has flanges 22 for mountingthe enclosure to a wall or in a control rack. An optional faceplate 23,FIG. 5, may be provided over the door for decorative or informationalpurposes and it may also be desirable to provide a bank of indicatorlights 24 at the front of the enclosure.

FIG. 3 illustrates the enclosure 10 with the door 16 removed. A thermalinsulation material 26, such as that sold under the trade designationDow Ethafoam 220, lines the inside of the chassis 12 and of the door 16(FIG. 5). A baffle plate 27 spans the upper portion of the chassis andis mounted with fasteners 28 to the side walls and top of the chassis12. A pair of terminal blocks 29 and 30, a fan 31 and a humidistat 33are mounted on the baffle plate 27. These devices are connected, alongwith others, in an environment control circuit which will be furtherdescribed below.

The lower portion of the chassis 12 forms a cavity 34 in which isdisposed a disc drive isolation module 36 which, together with theenclosure 10, makes up the isolation system 8. Referring particularly toFIGS. 4 and 5, the disc drive isolation module 36 is wedged between thefoam insulation 26 in the cavity 34 to keep it stationary relative tothe enclosure 10. However, the module 36 need not be wedged in thecavity in operation. In fact, as will become apparent below, the discdrive isolation module 36 performs its function of protecting the discdrive from shocks and vibrations whether it is mounted in the enclosure10 or not.

FIGS. 6 and 7 show the disc drive isolation module 36 removed from theenclosure 10. The module 36 is of generally hexahedron shape andincludes an outer body 38 which defines an inner space in which an innerbody 40 is mounted. A disc drive 41 is mounted within the inner body 40by being bolted or otherwise rigidly secured to a tray 42 which spansthe interior of the inner body and which is fastened to the sides of theinner body. The disc drive therefore is subjected to the same shocks andvibrations that the inner body 40 experiences. Preferably, the center ofgravity of the disc drive 41 is as close as possible to the center ofthe inner body 40.

The inner body 40 is mounted approximately concentric with the outerbody 38 so that it is out of direct contact with the outer body 38 andis isolated from the vibrations and shocks to which the outer body 38 issubjected. The inner body 40 has six degrees of freedom within the outerbody 38, three translational degrees of freedom in orthogonal directionsand three rotational degrees of freedom about orthogonal axes, so thatit can rotate or translate in any direction. This mounting is achievedin the preferred embodiment by suspending the inner body 40 from the topof the outer body 38 with a biasing means and supporting it from thebottom with another biasing means. The top biasing means is a pair ofconical springs 43 and the bottom biasing means is another pair ofconical springs 44. Since the top springs 43 are in tension and thebottom springs 44 are in compression, the springs 43 and 44 aredifferent from one another, being chosen to center the inner body withinthe outer body as closely as practical. Since the springs 43 and 44 areconical, they have non-linear stiffness characteristics to provide gooddynamic vibration characteristics over a broad range of frequencies.Also, the conical configuration is more stable radially than acylindrical spring.

The springs 43 and 44 are arranged so that they are diagonally opposedfrom top to bottom. That is, as viewed in FIG. 7, the top springs arepositioned at the right front and at the left rear corners and thebottom springs are positioned at the left front and at the right rearcorners. This diagonally opposed from top to bottom arrangement is alsoillustrated in FIG. 8. Since the inner body is symmetrical, thisarrangement results in the inner body being properly oriented within theouter body with only four springs. It also reduces "bobbing" of theinner body 40 within the outer body 38 which can occur with other springarrangements, such as it all four springs were on the top or bottom.

While the springs 43 and 44 function to isolate the inner body 40 fromvibration and low level shock, dampening means are provided between theouter and inner bodies to absorb higher level shocks. The dampeningmeans in the preferred embodiment is a pair of wedding cake-shaped foampads 46 adhesively or otherwise mounted on the inside of each of thehorizontal or vertical sides of the outer body (a total of 12 pads). Thevarying cross-sectional shape of the pads imparts non-linearforce/compression characteristics to the pads so that they becomeprogressively stiffer as they are compressed to resist direct contactbetween the inner and outer bodies for large shocks and yet provide agradual dampening for smaller shocks. The material of the dampeningmeans 46 has a relatively long response time, so that it is a gooddampener for infrequent shocks. A material found suitable in practice issolid under the trade designation Material No. C-3001-25 PSA by CabotCorporation, E.A.R. Division, Indianapolis, Indiana. Using thismaterial, the response time of the dampening means from near fullcompression is about two minutes.

Each pad 46 in the preferred embodiment terminates short of spanning theinner and outer bodies by about 6.35 mm (0.25 in). Like the springs 43and 44, each pair of pads 46 is diagonally opposed from the oppositepair of pads. This provides sufficient high level shock protection witha minimum number of pads.

The spacing between the ends of the pads 46 and the inner body 40 isimportant. The spacing permits a sufficient displacement of the innerbody 40 within the outer body 38 as the outer body 38 is subjected torelatively high amplitude, low frequency vibration to bring theacceleration forces to which the inner body 40 is subjected down toacceptable levels. This high amplitude, low frequency vibration iscommon in industrial environments and is not acceptable for theoperation of many disc drives. The spacing between the ends of the pads46 and the inner body 40 should be at least 0.89 mm (0.035 in.) to allowa sufficient displacement to isolate the disc drive from this type ofvibration.

It is also important that the inner body be symmetrical. This not onlyhelps center and orient the inner body 40 within the outer body 38 asmentioned above, but it also equalizes inertial moments about therotational axes to which the module is subjected.

The outer and inner bodies 38 and 40 are of generally the samehexahedron shape, with the inner body 40 being smaller than the outerbody 38. The construction of the outer and inner bodies 38 and 40 in thepreferred embodiment is particularly advantageous because it can beeasily and inexpensively provided. This is because both the outer body38 and the inner body 40 are each made up of six identical plates 49,one of which is shown in FIGS. 9 and 10.

Each plate 49 is preferably stamped from sheet aluminum. The plate 49has a flat rectangular inner portion 50 and two pairs of ears 51, eachpair being opposite from the other, and two pairs of ears 53, with eachpair being opposite from the other. The ears 51 and 53 are symmetricallydisposed along the edges of the rectangular portion 50 and are allformed in the same direction at about 45° angle to the rectangularportion 50. The only difference between the ears 51 and the ears 53 isthat each ear 51 is provided with inner 55 and outer 56 holes which areround, and each ear 53 is provided with inner 59 and outer 60 holeswhich are oblong. The centers of the holes in each ear are along a linewhich extends through the centers of the holes in the opposite ear.

Referring to FIGS. 6, 7 and 8, six plates 49 are assembled to provideeither the inner body 40 or the outer body 38 with the ears 53 alwaysoverlapping the ears 51. Therefore, the oblong holes 59 and 60 arealways on the outside, and the round holes 55 and 56 are always on theinside. When all of the panels are assembled together, fasteners 62 areinserted through one of the oblong holes and screwed into one of theround holes of each respective ear 53 and 51 to secure the plates 49together. If the smaller inner body 40 is being assembled, the fastenersare inserted through the oblong hole 59 and screwed into the round hole55 of each respective ear 53 and 51. If the larger outer body 38 isbeing assembled, the oblong hole 60 and the round hole 56 of eachrespective ear 53 and 51 are used.

Each plate 49 is stamped to provide means for mounting the springs 43and 44 to the inner and outer bodies 40 and 38, respectively. Four tabs63 are formed in a circular pattern in diagonally opposite corners ofthe rectangular portion 50. Referring to FIG. 11, each tab 63 forms aspace 64 between itself and the inner surface of the plate 49. A hole 65is formed concentric with the circular pattern of the tabs 63. Smallerholes 67 are formed at the other two corners of a rectangular patterndefined by the holes 65 and 67 and four holes 68 are formed intermediatethe holes 65 and 67.

Referring to FIGS. 4, 5 and 7, two of the holes 68 in each of the plates49 on the left and right sides of the inner body 40 are used to mountthe disc drive supporting tray 42 with fasteners 69. With the inner bodycompletely assembled, the springs 43 and 44 are loosely assembled to thetop and bottom plates 49, respectively, by inserting a fastener with asuitably large head through the small end of the spring and screwing thefastener into one of the holes 67. An annular PVC pad 72 is preferablyplaced between the small end of each spring 43 and 44 and the respectivetop or bottom plate 49 to reduce friction between the end of the springand the plate.

The inner body 40 with the springs 42 and 43 loosely attached is thenplaced inside the outer body 38, which, of course, must be done beforethe outer body is completely assembled. The inner body 40 is placedwithin the outer body 38 with the large end of the springs 42 and 43adjacent to the tabs 63. The assembly of the outer body 38 is thencompleted. Since the springs are only loosely attached to the innerbody, each spring can be rotated to thread its leading coil through thespaces 64 to be captured by the tabs 63. A PVC pad 71 to reduce frictionis also preferably placed between the large end of each spring and theouter body. A screw driver is then inserted through the holes 65 totighten the fasteners against the small ends of the springs.

Tests were performed subjecting the module 36 to shock and vibrationloads. The disc drive 41 tested with the module 36 was a 51.9 M byteWinchester technology head disc assembly. The disc drive tested had ahousing which enclosed a read/write mechanism. The sensor was secureddirectly to the read/write mechanism for each test. The plates 49 usedwere made from about 1.5 mm (0.060 inch) thick aluminum and were about22.5 cm (8.9 inches) square. The top springs 43 were made from 1.777 mm(0.070 inch) diameter music wire with a 2.386 mm (0.094 inch) pitch andan overall length of 19.036 mm (0.0750 inch). The bottom springs 44 weremade from 2.030 mm (0.080 inch) diameter music wire with a pitch of4.365 mm (0.172 inch) and an overall length of 34.898 mm (1.375 inches).Both springs had eight coils with the small end coil ground flat and thecoil diameter ranging from 7.208 mm (0.284 inch) to 45.051 mm (1.775inches) in increments of 5.406 mm (0.213 inch).

To test the disc drive alone, the housing of the disc drive was boltedto a vibration table to be vibrated along an axis parallel to the widthof the disc drive (from left to right as viewed in FIG. 4). Thevibration input to the housing was 0.152 mm (0.006 inch) peak to peakamplitude from 5 to 40 Hz and 0.5 G from 40-2000 Hz. Tracing A in FIG.12 illustrates the results. Tracing A shows that the read/writemechanism resonates at about 30 Hz, with an amplitude of about 0.761 mm(0.030 inch) and an acceleration of about 1.5 G. Also note that sincemost electric motors run at 3600 rpm, which is a multiple of 30 Hz, 30Hz is a fairly common frequency in industrial environments.

Tracing B shows the results of mounting the disc drive in the isolationmodule 36 and bolting the outer body 38 to the vibration table. The testwas conducted for the same input amplitude as above from 5-40 Hz but theinput was doubled to 1.0 G from 40-2000 Hz. The resonance at 30 Hz wascompletely eliminated and, even though the input from 40-2000 Hz wasdoubled, there were no objectionable vibrations experienced by theread/write mechanism.

The module was also tested for high level shock isolation. Again, thedisc drive was tested alone and then mounted on the module to comparethe results. A 15 G input applied over a period of 11 msec was appliedalong a direction parallel to the width of the disc drive. For the inputapplied directly to the disc drive housing, a sensor mounted on theread/write mechanism indicated an acceleration of about 80-100 G. Whenthe disc drive was mounted in the module 36 and the input was applied tothe outer body 38, this 80-100 G was reduced to about 2-3 G. Note thatallowing a displacement of the inner body of at least 0.89 mm (0.035in.) enables the input to exceed 15 G if applied over 11 msec or longer.

As indicated by these results, the disc drive isolation module 36dramatically attenuates the shocks and vibrations to which a disc drivewithin it is subjected. In an industrial environment, the attenuationafforded by the module can mean the difference between catastrophicdestruction of the disc drive or read/write errors and a smoothlyrunning automated machine or assembly line.

The module 36 is a unit and as such performs its function whether or notit is mounted in the enclosure 10. The module 36 is mounted in theenclosure 10 for reasons apart from isolating the disc drive fromexternal shocks and vibrations. A factory may be too hot, too cold, toodirty or too humid for the proper operation of the disc drive. Theenclosure 10 therefore provides a controlled temperature and humiditychamber for the disc drive to operate in.

The heat pump 14 and a pair of temperature sensors TS-1 and TS-2,mounted to the left side of the disc drive housing as shown in FIG. 4,make up part of the means for controlling the temperature inside theenclosure 10. The heat pump 14 of the preferred embodiment includes athermo-electric element 73 commercially available from Thermo-ElectricCooling America Company, Chicago, Illinois, under the trade designationModel No. AHP 1000. The thermo-electric element 73 is a solid stateactive heat exchanger having no moving parts so that the temperaturecontrol system of the enclosure 10 is extremely reliable. Thethermo-electric element 73 also makes the heat pump 14 simple toincorporate into the system 8, easy to mount and of low weight.

Referring to FIG. 5, the heat pump 14 has an upper and a lower flange75. Three threaded studs 76 are welded to and are spaced along eachflange 75 for securing the heat pump 14 to the chassis 12. A fasteningarrangement as shown in FIG. 13 is preferred to reduce the transmissionof vibrations from the heat pump 14 to the chassis 12 and to seal theinterior of the chassis 12 from the leakage of air around the studs 76.A washer 77, a neoprene gasket 78, a flange 79 of a sleeve 80 made froma vibration absorbing material, and another neoprene gasket 81 aresandwiched between the flange 75 and the chassis 12 around each stud 76.

Ths sleeve 80 and stud 76 extend through a hole in the chassis, with asmooth metal sleeve 83 threaded onto the stud 76 to prevent wear of thesleeve 80 by the threads of the stud. An annular element 84 of vibrationabsorbing material surrounds the sleeve 80, a neoprene gasket 85 abutsthe end of the sleeve 80 and closely surrounds the sleeve 83, and awasher 86 abuts the end of the sleeve 83 and surrounds each stud 76 onthe inside of the chassis 12. A nut 88 is threaded into the end of eachstud to clamp the sleeve 83 between the washer 86 and the flange 75 withthe sleeve 80 and element 84 in compression. A sleeve 80 and element 84found suitable in practice is commercially available from CabotCorporation, E.A.R. Division, Indianapolis, Indiana and is made frommaterial designated C-1100 by Cabot Corporation.

Referring again to FIG. 5, the thermo-electric element 73 has a coldside 90 having heat transfer fins 91 inside the enclosure 10 and a hotside 93 having heat transfer fins 94 outside the enclosure 10. The coldside 90 extends through an opening in the chassis 12 which is slightlylarger than the cold side and a neoprene gasket 97 surrounds thethermo-electric element 73 between the chassis 12 and the hot side 93 toprevent air leakage around the sides of the element 73. Heat absorbed atthe cold side 90 is pumped to the hot side 93 at a rate proportional tothe current passing through the element 73. In addition to thethermo-electric element 73, the heat pump 14 may include a fan 98 behindgrates 99 (FIG. 2) which blows relatively cool ambient air over the hotside fins 94 to expel the heat to the environment. Slots 100 (FIGS. 1-3)are formed in the side walls of the chassis 12 adjacent to the ends ofthe fins 94 to allow for the exit of warmed air from the fins 94.

The fan 31 blows air into the space behind the baffle plate 27 onto thecold side fins 91. The fins 91 are not as long as the interior of theenclosure 10 is wide so that cooled air can escape past the ends of thefins 91 and flow down into the cavity 34. The construction of the module36 is open, that is, the ears 51 and 53 form open spaces between them.The cool air circulates through the open spaces into the interior of theinner body 40 to cool the disc drive 41. In operation, the disc driveexpels about 33-35 watts of power which warms the air as it passes bythe disc drive. The air warmed by the disc drive is then sucked up intothe fan 31 to be recirculated through the enclosure.

When the disc drive is operating with the enclosure in ambienttemperatures cooling will usually be required. However, in someapplications it may be necessary to pre-warm the interior of theenclosure 10 before the disc drive can be started. For this purpose, theheat pump 14 also includes a 100 watt cartridge heater 103 which isembedded in the central portion of the cold side fins 91.

The element 73 and cartridge heater 103 are controlled by thetemperature sensors TS-1 and TS-2. The sensors TS-1 and TS-2 sense thetemperature of and around the disc drive housing to open or close acircuit connected to the element 73 and heater 103. In the preferredembodiment, TS-1 and TS-2 are bimetal-type switches.

Sensor TS-1 controls the element 73. Below about 40° C. (104° F.) thesensor TS-1 will be open so that the element 73 will be off. However,neither TS-1 nor TS-2 controls the fans 31 and 98, which are normallyon. As the temperature within the enclosure 10 rises past about 40° C.(104° F.), due for example to the heat generated by operating the discdrive, sensor TS-1 will close to turn the element 73 on to begin coolingthe interior of the enclosure 10. There is a differential of about 11°C. (20° F.) between the temperature at which the sensor TS-1 closes andthe temperature at which it opens. The element 73 will thereforecontinue to cool the interior of the enclosure 10 until TS-1 senses atemperature of about 29° C. (84° F.).

Sensor TS-2 controls the heater 103. Above about 22° C. (72° F.), sensorTS-2 is open so that the heater 102 is off. As the temperature fallsbelow about 22° C., TS-2 is closed so that the heater 103 will heat theinterior of the enclosure 103. As the temperature rises past about 22°C. (72° F.), TS-2 will open to shut off the heater 103. With a normalambient temperature, the temperature in the enclosure 10 will continueto rise due to the heat generated by the disc drive until the element 73turns on to cool the enclosure. However, if after the cartridge heaterturns off the temperature in the enclosure falls, the cartridge heaterwould not turn back on until somewhat below about 22° C. due to thedifferential of TS-2. The differential of TS-2 in the preferredembodiment is about 3° C. (6° F.) so that the heater 103 would turn backon at about 19° C. (66° F.).

Another pair of temperature sensors TS-3 and TS-4 are mounted on theright side of the disc drive housing as best shown in FIG. 5. Thesensors TS-3 and TS-4 set upper and lower limits on the operatingtemperature of the disc drive 41. If the sensed temperature is too highor too low, the disc drive motor will automatically be turned off by thesensors TS-3 and and TS-4. Like TS-1 and TS-2, TS-3 and TS-r are bimetalswitches in the preferred embodiment.

Sensor TS-3 determines the upper limit of the range of acceptableoperating temperatures for the disc drive 41. As the temperature sensedby TS-3 rises past about 55° C. (131° F.), TS-3 opens thereby cuttingoff power to the disc drive motor. Sensor TS-3 will not close to resumepower to the disc drive motor until it senses a temperature of about 52°C. (125° F.) due to its differential of about 3° C. (6° F.).

Sensor TS-4 determines the lower limit of the range of acceptableoperating temperatures for the disc drive 41. Below about 15° C. (59°F.), sensor TS-4 will be open to shut off the power to the disc drivemotor. As the temperature in the enclosure rises past about 15° C., TS-4closes to provide power to the disc drive motor. If for some reason thetemperature would then start to fall, TS-4's differential of about 3° C.(6° F.) would not allow it to re-open until the temperature reachedabout 12° C. (53° F.).

In summary of the temperature control means, below about 15° C. (59°F.), no power is provided to the disc drive motor but the cartridgeheater 103 is operating to heat the enclosure. At about 15° C., TS-4closes to provide power to the disc drive motor so that both the discdrive and the cartridge heater 103 are generating heat to raise thetemperature of the enclosure. When the temperature reaches about 22° C.(72° F.), TS-2 opens to shut the cartridge heater 103 off. The discdrive 41 continues to operate thereby generating heat to raise thetemperature of the enclosure. When the temperature reaches about 40° C.(104° F.), TS-1 closes to turn the element 73 on to reduce thetemperature inside the enclosure. If the temperature continues to rise,when it reaches about 55° C. (131° F.), TS-3 opens to turn the discdrive off.

However, even if the temperature inside the enclosure is acceptable,condensation can form on the disc or head which results in damage to thedisc drive or read/write errors. To prevent condensation, the humidistat33 monitors the relative humidity in the enclosure 10. The humidistat 33opens to turn the entire temperature control system including the fans31 and 98 off if the relative humidity rises above about 80%. Note thatit does not turn off the disc drive 41. It does not because the heatgenerated by the disc drive reduces the relative humidity in theimmediate vicinity of the disc drive. This heat is particularlyeffective to reduce the relative humidity in the vicinity of the discdrive when the environmental control system is not operating as the heatthen tends to concentrate around the disc drive, thereby lowering therelative humidity in that vicinity. Unless the temperature of the discdrive rises above about 50° C. (122° F.) so that the sensor TS-3 shutsit off, the heat generated by the disc drive will eventually lower therelative humidity throughout the interior of the enclosure and thehumidistat will close to resume power to the environment control system.The humidistat 33 used in the preferred embodiment was of the typehaving a nylon element to expand and contract to operate a switch.

A schematic diagram of a circuit 105 to control the temperature andhumidity as described above is shown in FIG. 14. 115 volt line power isadmitted to the enclosure 10 by the power cable 20. A circuit breaker106 should be provided, which is connected between one node of thehumidistat 33 and line power. The fans 31 and 98 are connected inparallel between ground and the other node of the humidistat 33. Alsoconnected in parallel between ground and the other node of thehumidistat 33 are TS-1, the element 73 and an LED indicator 108connected in series, and TS-2, the heater 103 and an LED indicator 109,connected in series. The LED indicators 108 and 109 are mounted alongthe front of the enclosure in the bank 24 to indicate when the element73 and heater 103, respectively, are on.

FIG. 15 illustrates a schematic view of a circuit for the out of rangetemperature control of the disc drive 41. A disc drive power supplyoutside of the enclosure 10 converts line power into 12 VDC and 5 VDCpower for the disc drive motor and the disc drive digital circuitry,respectively. The 12 and 5 VDC power lines are introduced into theenclosure 10 by one of the cables 18 and 19 and the 5 VDC is connecteddirectly to a 5 VDC input terminal of the disc drive. The sensors TS-3and TS-4 are connected in series between the 12 VDC input terminal ofthe disc drive 41 and the 12 VDC power supply, with the disc drive andpower supply suitably grounded. An LED indicator 111 may also beprovided in the bank 24 to indicate when the temperature is in theoperating range. Note that it may be desirable to provide other LEDindicators in the bank 24 such as one to indicate when the read/writehead is actuating.

All openings in the chassis 12 are sealed to prevent air leakage into orout of the enclosure 10. A neoprene gasket 113 resides between the door16 and an angle flange 115 which circumscribes and is welded to thechassis 12 (FIG. 5). Other neoprene gaskets or sealing means (not shown)seal the openings for the cables 18, 19 and 20, and the holes for thefasteners 28 of the baffle plate 27. Therefore, the interior of theenclosure is completely sealed from any air exchange with the outsideenvironment so that the air which is trapped within the enclosure 10when it is assembled remains in the enclosure 10. The humidity of theair that is trapped within the enclosure 10 may be controlled by placinga suitable dessicant within the enclosure 10.

The disc drive isolation system fully described above enables a discdrive to operate in an industrial environment. The system can be adaptedto protect almost any disc drive from shocks and vibrations which it mayotherwise be subjected to in the industrial environment. It alsoprovides a temperature and humidity controlled chamber for the discdrive which is extremely reliable. Therefore, operation of a disc drivein an industrial environment is no longer dependent upon thetemperature, humidity, cleanliness or vibration and shockcharacteristics of the industrial environment.

Various modifications and variations to the preferred embodiment will beapparent to those skilled in the art which will still embody theinvention. For example, the invention is not limited to being used witha Winchester technology disc drive, although that type of disc drive isadvantageous for its large memory capacity. Therefore, the invention isnot intended to be limited to the scope of the preferred embodiment, butonly by the claims which follow, except as otherwise required by law.

I claim:
 1. A disc drive isolation module for sequestering a disc drivedevice from vibration and shock applied to the exterior of the module,said disc drive including an information storage disc and means forstoring information on said disc and/or means for retrieving informationfrom said disc, comprising:an outer body of generally hexahedron shapehaving spaced apart top and bottom sides, spaced apart left and rightsides, and spaced apart front and rear sides so that said outer bodydefines an inner space; an inner body of generally hexahedron shapesmaller than said outer body and having spaced apart top and bottomsides, spaced apart left and right sides, and spaced apart front andrear sides, the inner body fitting within the inner space defined by theouter body with the sides of the inner body spaced apart from the sidesof the inner body; first biasing means connected between the top sidesof the inner and outer bodies for suspending the inner body within theouter body; second biasing means connected between the bottom sides ofthe inner and outer bodies for suspending the inner body within theouter body; damping means between the inner and outer bodies on the top,bottom, left, right, front and rear sides of the inner and outer bodies;and means for rigidly mounting the disc drive within the inner body. 2.A disc drive isolation system as in claim 1, wherein the first biasingmeans comprises a pair of conical springs and the second biasing meanscomprises another pair of conical springs, the springs of the firstbiasing means being diagonally opposed from the springs of the secondbiasing means.
 3. A disc drive isolation system as in claim 1, whereinthe damping means comprises foam pads secured to the outer body, a pairof said foam pads being secured to each side of the outer bodydiagonally opposite from the pads secured to the opposite side of theouter body, each of said pads having a varying cross section to impartnonlinear stiffness characteristics to the pad.
 4. A disc driveisolation system as in claim 1, wherein each of the inner and outerbodies comprises six identical plates which are fastened together toform the respective inner and outer bodies, each said plate having aflat rectangular inner portion, two pairs of first ears and two pairs ofsecond ears, said ears being symmetrically disposed along the edges ofthe rectangular portion with each pair of first ears being opposite fromthe other pair of first ears and with each pair of second ears beingopposite from the other pair of second ears, each ear having an outerand an inner hole, the centers of the holes in each ear lying on a linewhich extends through the centers of the holes in the opposite ear, theears of adjacent plates being fastened together to form either the inneror the outer body, depending upon which holes in the ears are used tofasten the plates together.
 5. A disc drive isolation system as in claim4, wherein the ears of each plate are formed in the same direction atapproximately a 45° angle with the rectangular inner portion and defineopen spaces between them so that air can circulate into and out of theinner body.
 6. A disc drive isolation system as in claim 4, wherein theholes in the first ears are circular in shape and the holes in thesecond ears are oblong in shape, the plates being assembled togetherwith the second ears always overlapping the first ears.
 7. A disc driveisolation system as in claim 4, wherein the first biasing meanscomprises a pair of conical springs and the second biasing meanscomprises another pair of conical springs, the springs of the firstbiasing means being diagonally opposed from the springs of the secondbiasing means, the springs being mounted with their larger diameter endsadjacent to the outer body and with their smaller diameter ends adjacentto the inner body, diagonally opposite corners of the rectangularportion of each plate being provided with strapes which are formedinwardly to define a space between each strap and the rectangularportion, the strapes being arranged in a circular pattern having adiameter about equal to the diameter of the larger end coil of thesprings, a relatively larger hole formed at the center of said circularpattern and relatively smaller holes formed at each of the other twocorners of the rectangular portion so that the larger end coil of aspring can be threaded through the spaces defined by the straps and thesmaller end coil of the spring can be fastened to the inner body byinserting a suitable driver tool through the relatively larger hole inthe outer body to connect a fastener in the adjacent relatively smallerhole in the inner body.
 8. A disc drive isolation system forsequestering a disc drive device from vibration and shock, said discdrive including an information storage disc and means for storinginformation on said disc and/or means for retrieving information fromsaid disc, comprising:a structurally rigid outer body defining a firstset of two spaced apart and parallel planes and a first inner space aninner body within said first inner space for supporting said disc driveout of direct contact with said outer body, said inner body defining asecond set of two spaced apart and parallel planes within said firstinner space, said second set of planes being parallel to said first setof planes and defining between them a second inner space which iscontained by said first inner space; means for rigidly mounting a discdrive to the inner body within the second inner space; and first andsecond biasing means for supporting said disc drive and inner bodywithin said second inner space with three translational degrees offreedom in orthogonal directions and three rotational degrees of freedomabout orthogonal axes, said first and second biasing means being locatedbetween the outer body and the inner body with said first biasing meansextending between one plane of the first set of planes and an adjacentplane of the second set of planes and with the second biasing meansextending between the other plane of the first set of planes and theother plane of the second set of planes.
 9. A disc drive isolationsystem as in claim 8, wherein the first and second sets of planes arehorizontal and the first biasing means includes a pair of extensionsprings depending from a top plane of the first set of planes and asecond biasing means including a pair of compression spring extendingfrom a bottom plane of the first set of planes, the springs of the firstbiasing means being diagonally opposed from top to bottom from thesprings of the second biasing means.
 10. A disc drive isolation systemas in claim 8, further comprising damping means including foam padsbetween the outer and inner bodies, a pair of said pads being adjacentto each plane of the first set of planes, each said pair of pads beingdiagonally opposite from side to side from the pair of pads which areadjacent to the other plane of the first set of planes.
 11. A disc driveisolation system as in claim 8, wherein each of the outer and innerbodies are of generally hexahedron shape and each comprises sixidentical plates which are fastened together to form the respectiveinner and outer bodies, each said plate having a flat rectangular innerportion, two pairs of first ears and two pairs of second ears, said earsbeing symmetrically disposed along the edges of the rectangular portionwith each pair of first ears being opposite from the other pair of firstears and with each pair of second ears being opposite from the otherpair of second ears, each ear having an outer and an inner hole, thecenters of the holes in each ear lying on a line which extends throughthe centers of the holes in the opposite ear, the ears of adjacentplates being fastened together to form either the inner or the outerbody, depending upon which holes in the ears are used to fasten theplates together.
 12. A disc drive isolation system as in claim 11,wherein the ears of each plate are formed in the same direction atapproximately a 45° angle with the rectangular inner portion and defineopen spaces between them so that air can circulate into and out of theinner body.
 13. A disc drive isolation system as in claim 11, whereinthe holes in the first ears are circular in shape and the holes in thesecond ears are oblong in shape, the plates being assembled togetherwith the second ears always overlapping the first ears.
 14. A disc driveisolation system as in claim 11, wherein the first biasing meanscomprises a pair of conical springs and the second biasing meanscomprises another pair of conical springs, the springs of the firstbiasing means being diagonally opposed from the springs of the secondbiasing means, the spring being mounted with their larger diameter endsadjacent to the outer body and with their smaller diameter ends adjacentto the inner body, diagonally opposite corners of the rectangularportion of each plate being provided with straps which are formedinwardly to define a space between each strap and the rectangularportion, the straps being arranged in a circular pattern having adiameter about equal to the diameter of the larger end coil of thesprings, a relatively larger hole formed at the center of said circularpattern and relatively smaller holes formed at each of the other twocorners of the rectangular portion so that the larger end coil of aspring can be threaded through the spaces defined by the straps and thesmaller end coil of the spring can be fastened to the inner body byinserting a suitable driver tool through the relatively larger hole inthe outer body to connect a fastener in the adjacent relatively smallerhole in the inner body.